114 REPORT 1861. 



the dry substance no caustic soda can be dissolved out by alcohol. Hence 

 he concluded that the black ash consists of a mixture of carbonate of soda, 

 caustic lime, and monosulphide of calcium, and that when the mass is treated 

 with water, caustic soda and carbonate of lime are formed, the monosulphide 

 of calcium itself being insoluble in water. This theory of the composition 

 of black ash is now generally adopted by chemists practically engaged in 

 aliiali -making, and has received confirmation by the subsequent analyses of 

 Mr. F. Claudet and others. 



The growth of the soda-ash manufacture has been so rapid, and so many 

 changes have been caused by it in the chemical arts, that a short sketch of 

 its history may with great propriety be added to this portion of our subject — 

 this sketch being in the main an abridgement of Mr. Gossage's paper read 

 before the Section. Previous to 1793, soda was made almost entirely from 

 the ashes of sea-weed obtained from Alicante, Sicily, Teneriffe, Scotland, and 

 Ireland. Potash from Russia, France, and America supplied its place to a 

 large extent ; now, however, soda supplies the place of potash, even in those 

 countries from which we formerly obtained potash. In ITOl a French Com- 

 mission decided that Leblanc's soda-ash process was the best proposed. The 

 Government made it known to the public in 1797. The inventor died in 

 poverty; but many manufacturers rose up in France and obtained great suc- 

 cess. It was little known in this country till 1823, when the duty of j630 a 

 ton was taken off salt. 



In connexion with soda, muriatic acid and chlorine must be named. 

 Although Scheele, a Swede, discovered chlorine, Berthollet discovered its 

 bleaching properties. The process was introduced into Scotland by Professor 

 Copeland of Aberdeen; and in 1798 Mr. Charles Tennant of Glasgow 

 patented a solution of chloride of lime as a bleaching-liquor, which was fol- 

 lowed up by the invention of the present bleaching-powder. When com- 

 mon salt is decomposed by sulphuric acid, the muriatic acid from which the 

 chlorine is obtained is set free ; when this process was performed by bleachers 

 the duty on the salt was remitted, but they were compelled to throw away all 

 the sulphate of soda formed— -a strange and most wasteful act. This con- 

 tinued till ISl-i. About this time occurred the expiration of Tennant's patent 

 for bleaching ; and crystals of carbonate of soda were gradually introduced at 

 3630 per ton. Mr. Losh, of Newcastle, had made use of Leblanc's process 

 almost from its publication, but on a small scale. In 1802 he sold soda-crystals 

 at £60 per ton ; the present price is £i 10s. But in 1823 may be dated the 

 commencement of the soda-ash manufacture in this country, when Mr. James 

 Muspratt erected his works at Liverpool. 



The decomposition of the salt was made chiefly in open furnaces ; so that 

 an enormous amount of muriatic acid was sent into the air, and soda-works 

 were removed from towns when the Woulfe's apparatus was not used for con- 

 densation. To remedy this loss, Mr. Gossage invented, in the year 1836, the 

 coke tower as at present used. The acid gases percolate through a deep 

 bed of coke, which fills a high tower, and which is supplied with water 

 trickling through the porous material. Mr. Gossage and Mr. Shanks are said 

 to have so purified the gas at Messrs. Crossfield's works at St. Helens, that it 

 did not even render a solution of nitrate of silver turbid. 



In 1838, when the King of the Two Sicilies monopolized the trade in 

 sulphur, it was raised in price from £5 to £14 per ton, when the Irish pyrites 

 began to be used. This again led to the extraction of the copper from 

 the spent pyrites, and also of the silver, a process commenced by Mr. Gos- 

 sage in 1850. Mr. John Wilson began to extract the gold, but without com- 

 mercial success. 



